[LLVMbugs] [Bug 10171] New: Substitute unpckhpd, unpcklpd and movddup for shufpd

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=10171

           Summary: Substitute unpckhpd, unpcklpd and movddup for shufpd
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: X86
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: jmuizelaar at mozilla.com
                CC: llvmbugs at cs.uiuc.edu


shufpd    $0, %xmm0, %xmm0 ## xmm0 = xmm0[0,0]
can be replaced with unpcklpd when restricted to sse2 and movddup when using
sse3.

shufpd    $3, %xmm0, %xmm0 ## xmm0 = xmm0[1,1]
can be replaced with unpckhpd

These variants are faster on some processors and take a byte less to encode.
moddup also allows the source to be different than the destination which can
allow a copy to be avoided.

GCC also makes these substitutions.

-- 
Configure bugmail: http://llvm.org/bugs/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.